Design and Fabrication of the Reliable GaN Based Vertical-Cavity Surface-Emitting Laser via Tunnel Junction

Ching-Hsueh Chiu,Cheng-Yuan Chen,Hao-Chung Kuo,Yen-Wei Yeh,Tingzhu Wu,Yu-Tzu Chen,Chin-Wei Sher,Ya-Hsuan Shih,Po-Tsung Lee,Chih-Chiang Shen,Yun-Ting Lu,Tien-Chang Lu

doi:10.3390/cryst9040187

Abstract

In this study, we theoretically designed and experimentally fabricated an InGaN vertical-cavity surface-emitting laser (VCSEL) with a tunnel junction (TJ) structure. From numerical simulation results, the optical loss of the device can be reduced by a TJ structure. Additionally, the leakage current of the VCSEL with TJ structure was much smaller than that of the VCSEL with an Indium-Tin-Oxide (ITO) layer. We have been demonstrated that laser output performance is improved by using the TJ structure when compared to the typical VCSEL structure of the ITO layer. The output power obtained at 2.1 mW was enhanced by a factor of 3.5 by the successful reduction of threshold current density (Jth) from 12 to 8.5 kA/cm2, and the enlarged slope efficiency was due to less absorption in VCSEL with a TJ structure. Finally, the samples passed the high temperature (70 °C) and high operation current (1.5 × Jth) test for over 500 h.

Highlights

The GaN-based material system features high emission efficiency with the characteristic of direct-bandgap, whose emission wavelength can cover the overall visible light spectrum by tuning alloy compositions [1,2,3,4]
The blue line is the distribution of refractive index for vertical-cavity surface-emitting laser (VCSEL) while the black black line is the distribution of standing wave profile for VCSELs
We demonstrated an InGaN VCSEL with a tunnel junction (TJ) structure experimentally and

Summary

Introduction

The GaN-based material system features high emission efficiency with the characteristic of direct-bandgap, whose emission wavelength can cover the overall visible light spectrum by tuning alloy compositions [1,2,3,4] These advantages enable these materials to have many potential applications. On the other hand, compared to edge-emitting lasers and light-emitting diodes (LEDs), vertical-cavity surface-emitting lasers (VCSELs) have the superiority of low power consumption, circular beam shape, high modulation response, and low divergence angles [5,6,7,8]. If green and blue forms of this device are united with red-emitting GaAs VCSELs, this could spawn incredibly small, wearable projectors for full-color displays [9,10,11,12].

Methods

Results

Conclusion